• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.90-93
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• 2004

In this work, we have used different techniques for the surface passivation: conventional thermal oxidation (CTO), rapid thermal oxidation (RTO), and plasma-enhanced chemical vapour deposition (PECVD). The surface passivation qualities of eight different single and combined double layer have been investigated both on the phosphorus non-diffused p-type FZ silicon and on phosphorus diffused emitter of 100 ${\Omega}/Sq$ and 40 ${\Omega}/Sq$. In the single layer, silicon dioxide $(SiO_2)$ passivates good on the emitter while silicon nitride (SiN) passivates better than on the non-diffused surface. In the double layers, CTO/SiN1 passivates very well both on non-diffused surface on the emitter. However, RTO/SiN1 and RTO/SiN2 stacks are more suitable for surface passivation in solar cells caused by a relatively good passivation qualities and the low optical reflection. Applying these stacks in solar cells we achieved 18.5 % and 18.8 % on 0.5 ${\Omega}$ cm FZ-Si with planar and textured front surface, respectively. The excellent open circuit voltage $(V_{oc})$ of 675.6 mV is obtained the planar cell with RTO/SiN stack.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.3
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• pp.231-236
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• 2005

To investigate the electrical properties at the single grainboundary of ZnO varistors, micro-electrodes were fabricated on the surface which was polished and thermally etched. Our micro-electrode had 2000 $\AA$ silicon nitride layer between micro-electrode and ZnO surface. This layer was deposited by PECVD and etched by RIE after photoresistor pattering process using by mask 1. The metal patterning of micro-electrodes used lift-off method. We found that the breakdown voltage of single grainboundary is about 3.5∼4.2 V at 0.1 mA on I-V curves. Also, capacitance-voltage measurement at single grainboundary gave several parameters( $N_{d}$, $N_{t}$, $\Phi$$_{b}$, t) which were related with grainboundary.ary.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.21-26
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• 1995

Highly sensitive and mechanically stable gas sensors have been fabricated using the microfabrication and micromaching techniques. The sensing material used to detect the offensive trimethylarnine ((CH$_{3}$)$_{3}$N) gas is 6 wt% $Al_{2}$O$_{3}$-doped, 1000.angs.-thick ZnO deposited by r. f. magnetron sputtering. The optimum operating temperature of the sensor is 350.deg.C and the corresponding heater power is about 85mW. Excellent thermal insulation is achieved by the use of a double-layer structure of 0.2.mu.m -thick silicon nitride and 1.4.mu.m-thick phosphosilicate glass(PSG) prepared by low pressure chemical vapor deposition(LPCVD) and atmospheric pressure chemical vapor deposition(APCVD), respectively. The sensors are mechanically stable enough to endure at least 43, 200 heat cycles between room temperature and 350.deg. C.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.464-468
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• 2003

The double layers of $SiO_2$/$Si_3$$N_4$ have superior charge storage stability than a single layer of $SiO_2$. Many researchers are very interested in the charge storage mechanism of $SiO_2$/$Si_3$$N_4$ [1,2]. In this paper, the electrical characteristics of thermal oxide and atmospheric pressure chemical vapor deposition (APCVD) of $Si_4$$N_4$ have been investigated and explained using high frequency capacitance-voltage measurements. Additionally, this paper will describe capacitance-voltage characteristics for double layers of $SiO_2$/$Si_4$$N_4$ by "Athena", a semiconductor device simulation tool created by Silvaco, Inc.vaco, Inc.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.6-10
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• 2009

In this paper, a selective area growth (SAG) of a GaN/AlGaN double heterostructure (DH) has been performed on r-plane sapphire substrate by using the mixed-source hydride vapor phase epitaxy (HVPE) with multi-sliding boat system. The SAG-GaN/AlGaN DH consists of GaN buffer layer, Te-doped AlGaN n-cladding layer, GaN active layer, Mg-doped AlGaN p-cladding layer, and Mg-doped GaN p-capping layer. The electroluminescence (EL) characteristics show an emission peak of wavelength, 439 nm with a full width at half maximum (FWHM) of approximately 0.64 eV at 20 mA. The I-V measurements show that the turn-on voltage of the SAG-GaN/AlGaN DH is 3.4 V at room temperature. We found that the mixed-source HVPE method with a multi-sliding boat system was one of promising growth methods for III-Nitride LEDs.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.221-227
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• 1997

The Pd/NiCr gate MISFET-type sensors were fabricated for detecting hydrogen dissolved in high-capacivity transformer oil. To improve stability and high concentration sensitivity of the sensor, Pd/NiCr double catalysis metal gate was used. To reduce the serious gate voltage drift of the sensor induced by hydrogen, the gate insulators of 2 FETs were constructed with double layer of silicon dioxide and silicon nitride. The hydrogen sensitivity of the Pd/NiCr gate MISFET is about a half of Pd/Pt gate MISFET's sensitivity but the Pd/NiCr gate MISFET has good stability and high concentration detectivity up to 1000 ppm.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.12 s.117
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• pp.1272-1278
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• 2006

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin(Au/Sn) eutectic solder bonding. The membrane chip has $2.5mm{\times}2.5mm$, 0.5${\mu}m$ thick low stress silicon nitride membrane, $2mm{\times}2mm$ Au/Ni/Cr membrane electrode, and 3${\mu}m$ thick Au/Sn layer. The backplate chip has $2mm{\times}2mm$, 150${\mu}m$ thick single crystal silicon rigid backplate, $1.8mm{\times}1.8mm$ backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50{\sim}60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is 39.8 ${\mu}V/Pa$(-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.273-278
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• 2021

Here, we studied the change in the mechanical stiffness of a diaphragm according to the corrugation pattern. The diaphragm consists of a silicon oxide and nitride double layer; a corrugation pattern was formed by dry etching, and the diaphragm was released by wet etching. The fabrication of the thin film was verified using focused ion beam and scanning electron microscopy images. The mechanical stiffness of the diaphragm was obtained by measuring the surface vibration using a laser Doppler vibrometer while applying external sound pressure. Flat squares, diaphragms with square corrugations, and circular corrugation patterns were measured and compared. The stiffness of the diaphragm with a corrugation structure was found to be smaller than that without a corrugation structure; in particular, circular corrugation showed a better effect because of the high symmetry. Furthermore, the effect of corrugation was theoretically predicted. The proposed corrugated diaphragm showed comparable flexibility with the state-of-the-art MEMS microphone diaphragm.

• Structural Engineering and Mechanics
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• v.64 no.3
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• pp.361-379
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• 2017

In this article, the vibration behavior of double-bonded sandwich microplates with homogeneous core and nanocomposite facesheets reinforced by carbon nanotube and boron nitride nanotube under multi physical fields such as 2D magnetic and electric fields is investigated. Symmetric and un-symmetric distributions of nanotubes are considered for facesheets of sandwich microplates such as uniform distribution and various functionally graded distributions. The double-bonded sandwich microplates rest on visco-Pasternak foundation. Material properties of sandwich microplates are obtained by the extended rule of mixture. The sinusoidal shear deformation theory (SSDT) is employed to describe displacement fields of sandwich microplates. Also, the dimensionless natural frequency is obtained by classical plate theory (CPT) and compared with the obtained results by SSDT. It can be seen that the obtained dimensionless natural frequencies by CPT are higher than SSDT. In order to study the material length scale parameters, modified strain gradient theory at micro scale is utilized and then, the equations of motion are derived using Hamilton's principle. The effects of different parameters such as foundation parameters including Winkler, shear layer and damping coefficients, various distributions and volume fraction of nanotubes, core to facesheet thickness ratio, aspect and side ratios on the dimensionless natural frequencies are discussed in details. The results of present work can be used to optimum design and control of similar systems such as micro-electro-mechanical and nano-electro-mechanical devices.

• Journal of Sensor Science and Technology
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• v.9 no.2
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• pp.113-119
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• 2000

In this work, Pd/Pt gate MISFET sensor using Pd membrane was fabricated to detect the hydrogen in DI water. A differential pair-type was used to minimize the intrinsic voltage drift of the MISFET. To avoid hydrogen induced drift of the sensor, the silicon dioxide/silicon nitride double layer was used as the gate insulator of the FET's. In order to eliminate the blister formation on the surface of the hydrogen sensing gate metal, Pd/Pt double metal layer was deposited on the gate insulator. For this type of application sensors need to be isolated from the DI water, and a Pd membrane was used to separate the sensor from the DI water. The output voltage change due to the variation of hydrogen concentration is linear from 100ppm to 500 ppm.